The particular design of muscles and bones in the neck and limbs of the turtle allow that it can draw in its exposed parts such that an attacker can find nothing
but hard shell to bite.

A. allow that it can draw in its exposed parts such that
B. allow it to draw in its exposed parts, and so
C. allows for it to draw in its exposed parts and that
D. allows that it can draw in its exposed parts, and so
E. allows it to draw in its exposed parts, so that

Here the subject is Singular(Design),and not plural.So you require singular verb,hence eliminating others.Finally ans is e,clear in meaning with so that.Whats the Oa?

I htink the Answer is E.Please correct if I am wrong

yes, e is the correct answer.

you should definitely eliminate based on subject-verb agreement first, because such agreement is always clear-cut and unambiguous (there can be no argument about whether a subject or verb is singular or plural). the subject, as has already been correctly asserted on this thread, is 'design'; the subsequent nouns muscles, bones, neck, and limbs are disqualified because they are objects of prepositions. therefore, we need the singular 'allows', so choices a and b are eliminated.

choice d:
'allows that it can...' is an incorrect idiom.
'...and so', while not ungrammatical, departs somewhat from the intended meaning of the original: so that (the original construction) implies a sense of purpose, intent, or design, while and so merely implies consequence, whether designed or arbitrary. for instance:
jim left his parents' back door open so that his friends can come take the liquor --> jim left the door open with this particular nefarious purpose in mind
jim left his parents' back door open, and so his friends can come take the liquor --> jim happened to leave the back door open, an oversight allowing his less straitlaced friends access to the alcohol

choice c:
'allows for it to...' is at best wordy, because the word 'for' serves no grammatical purpose whatsoever, and at worst an incorrect idiom. i of course cannot say which explanation the gmat would give.
'and that' is simply wrong, as there's no other 'that' to which it can be parallel.

Ron,

In your examples for right usage of "so that" and "and so", i need to know what if we replace "and so" with "so". As shown below:

jim left his parents' back door open, and so his friends can come take the liquor.

Edited:
jim left his parents' back door open, so his friends can come take the liquor.

I thought "and so" is a term which is using two conjunctions together. So I thought it is redundant to put "and" before "so". Please let me know if in any GMAT SC question I find two options having "and so" and "so", then which one to chose ? (Considering no other error in those sentences).

Thanks!

GeeMate.

i THINK (i'm not 100% sure) that you'll see either "so that" or "and so". i don't think you'll see "so" by itself on this exam.

here's the difference:
"so that" is followed by the INTENTION of some action, usually (but not always) using "could/would/can/will VERB".
if you see "so" by itself, it will also have this meaning.

"and so" is like "thus"; it gives a CONSEQUENCE or RESULT of the previous clause.

re: your examples


this could work. it's basically equivalent to, "because jim left his parents' back door open, his friends can come take the liquor."
this sentence DOES NOT imply that this was jim's intention in leaving the door open.

this sort of construction is more commonly used with verbs in simple tenses, describing what actually happens/happened.
e.g., [i]jim left his parents' back door open, and so his friends came and took the liquor"



this means that jim left the door open WITH THE INTENTION of allowing his friends to steal the liquor.
because the first verb ("left") is in the past tense, the second verb should be "could" instead of "can" (note that "could" is the past tense of "can").



in the second one, it's a conjunction.
in the first ("and so"), it's an adverb. it's almost exactly the same as "and thus".